Added r1cs ppzksnark proving scheme and some tests.

src/main.rs

@@ -1,7 +1,16 @@
 extern crate tinysnark;
+extern crate rand;
+
+use tinysnark::{Proof, Keypair, FieldT, LinearTerm, ConstraintSystem};
 
 fn main() {
     tinysnark::init();
 
-    tinysnark::test();
+    let mut cs = ConstraintSystem::new(1, 2);
+    cs.add_constraint(
+        &[LinearTerm{coeff: FieldT::one(), index: 2}],
+        &[LinearTerm{coeff: FieldT::one(), index: 3}],
+        &[LinearTerm{coeff: FieldT::one(), index: 1}]
+    );
+    assert!(cs.test(&[100.into()], &[10.into(), 10.into()]));
 }